I do have to applaud Real in their efforts to continue development on a "dead" format like mp3. Granted, mp3 is not technically dead but most people either use mpeg-4 AAC (the people who have iPods) or people use WMA (they were either suckered in through Windows XP or they use online music subscription services). Even though the Helix mp3 encoder hasn't reached the quality of the current Lame mp3 encoder, it is still blazing fast and has much better quality than the Fraunhoffer mp3 encoder. I remember some Hydrogenaudio members conducting listening tests using the Helix mp3 encoder, Lame, Fraunhoffer, and a low anchor mp3 encoder back from 1998. Helix came in second but it beat everyone on encoding speeds.
As far as using iTunes AAC, it is a good format, there is no doubt about that. Honestly, I would be using iTunes AAC if I didn't have a car CD deck that played mp3 CD's. Its seemless integration with both the iPod and iTunes make it a good choice for the not so tech savy people. Still, ripping with EAC and encoding with Lame mp3 takes about 2 minutes to initially setup (if that) and takes about 5 extra seconds when adding the tracks to your iTunes library. Don't be scared by all the -V 4 --vbr-new mumbo jumbo, it is just another way of saying 160kbps VBR.
If you are using iTunes AAC, I would recomend going with 128kbps VBR AAC. Serisously, do not go above 192kbps VBR as it is just a waste of space. Also keep in mind that a good pair of headphones will beat most home theater systems (and most car stereo systems) in terms of audio quality and the ability to spot defects in lossy audio. When you listen to music through a home theater system, you are not in a sound isolated room. Sound escapes the room so you are not hearing everything. Additionally, you are a minimum of 1 foot away from the speakers, you would be able to hear the flaws of lossy audio if the speakers were right up against your ears. Also, your home theater system can be blocked out by other noises from the outside world. The same pretty much goes for car stereo systems. Unless you have a 1000 watt amp (even then, lossy is fine) with some high end speakers and you have sealed your car off with goop, then lossy 128kbps VBR mpeg-4 AAC will be just fine. 224, 256, and 320kbps mpeg-4 AAC are just a waste of space as they don't effectively use the "advantages" of the mpeg-4 AAC format. Some people will say that 192kbps is the best option for mpeg-4 AAC encoding but most of these people use the Apple stock earbuds as well. If you are using the stock Apple earbuds, then definately use 128kbps VBR mpeg-4 AAC.
I have a computer (see specs in sig) that I hook up to my Logitech Z-680 speaker system. The speakers are a little old but they are able to pump out 1000 watts of max power and 500 watts of RMS power (normal use). My notebook has a Sigmatel C-Major soundchip (one of the best brands out there) and I hook it up to my speakers using a digital coaxil cable. Even with all that quasi-serious equipment, I still can't perceive a difference between the lossless source and a 128kbps VBR mpeg-4 AAC file encoded with iTunes. Well, I can when I really turn up the music, put my face right next to all the speakers, and concentrate really hard. This is very uncomfortable, damaging to the ears, and you definately won't be listening to your music this way at all.